<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        .inner {
            width: 50px;
            height: 100px;
            background-color: red;
            float: left;
        }

        .inner span {
            font-size: 14px;
            width: 14px;
            line-height: 14px;
            padding: 29px 18px;
            display: inline-block;
            background-color: #00FF00;
        }

        .select {
            width: 200px;
        }
    </style>
</head>
<body>
<div>
    <div class="inner select">
        <span>
            第一个
        </span>
    </div>
    <div class="inner">
           <span>
            第二个
        </span>
    </div>
    <div class="inner">
           <span>
            第三个
        </span>
    </div>
    <div class="inner">
           <span>
            第四个
        </span>
    </div>
    <div class="inner">
           <span>
            第五个
        </span>
    </div>
</div>
</body>
<script src="js/jquery-1.11.3.js"></script>
<script>
    $(".inner").mouseover(function () {
        $(this).stop(true,true).animate({"width": "200px"},1000).siblings().stop(true,true).css({"width": "50px"});
    });
</script>
</html>